Heretofore, certain types of polymers or copolymers were blended with polyvinyl chloride (PVC) resins to increase the glass transition temperature thereof. Such blends containing the glass transition temperature improving polymers or copolymers generally were unsatisfactory for various melt type fabrication processes such as custom injection molding (CIM) applications. When glass transition temperature improving polymers or copolymers having a low inherent viscosity in and of themselves were blended with PVC resins, the powder flux in various processing devices such as an extruder, a Bandbury, a mill, or an injection molding machine, was often unsatisfactory. Hence, high glass transition temperature polymers or copolymers were utilized having high inherent viscosities. Such high inherent viscosities decreased the melt flow when blended with PVC and limited the usefulness thereof in melt type fabrication processes.